The present invention relates to a method for preparation of ultrathin magnetic layer on semiconductors and the magnetic structure so prepared, especially to a method for preparing ultrathin magnetic layer with fixed-coercive force on semiconductor and the magnetic structure so prepared.
The research of metal/semiconductor interfaces has been intensively made by scientists and the industry in the past decades. Within this broad field, forming a magnetic layer on semiconductor substance in a nanometer scale is a newly developed technology. As the standards of electronic components and data recording media have reached a level such that magnetic structure has to be fabricated under the scale of nanometer, the thickness of magnetic layer must be reduced to several to tens of angstrom, whereby the size of devices may be reduced and unit density may be increased. Under such a scale, the nanometer-scaled magnetic structure so prepared must provide desired magnetic properties. As a result, preparing a nanometer-sized magnetic structure with desired magnetic properties has become a task of scientists and engineers ii this field. In addition, to reduce the thickness of magnetic layer on magnetic structures to the limitation of ultrathin has been an aim of researchers.
U.S. Pat. No. 6,317,045 disclosed a physical vapor deposition device for forming a metallic layer o a semiconductor wafer. In this invention, the PVD device provides an electric field generator for forming a vertical electric field to guide the metallic ions toward the wafer chuck at a slant angle. As a result, the deposition efficiency of magnetic layer at the sidewalls of the holes in the semiconductor wafer may be improved.
Due to the intensive research on magnetic films, the basic element of magnetic structures, it has been found that the magnetic properties of a magnetic film will be significantly influenced, if an interface layer is added between the magnetic film and its substrate. It has also been realized that variations in physical properties of the magnetic film, when the thickness of tile magnetic film is xe2x80x9cultrathinxe2x80x9d, will become decisive factors for the magnetic properties of the magnetic structure. In order to prepare an ultrathin magnetic layer on a semiconductor substrate, it is necessary to overcome or make good use of these factors.
One objective of this invention is to provide a novel method of preparation of ultrathin magnetic layer on semiconductors.
Another objective of this invention is to provide a method for preparation of ultrathin magnetic layer on semiconductors with fixed-coercive force.
Another objective of this invention is to provide a method of preparing a magnetic layer on semiconductor substrate with the help of a non-ferromagnetic metal buffer layer.
Another objective of this invention is to provide a magnetic structure prepared from the above methods.
According to the method for preparation of ultrathin magnetic layer on semiconductor or this invention, a non-ferromagnetic metal buffer layer thinner than 40 ML is formed on the semiconductor substrate on which the magnetic layer is to be prepared. According to experiments, the thickness of the non-ferromagnetic metal buffer layer may be 0.5-9 ML, preferably 1-8 ML, most preferably 1.5-6 ML. Thereafter, the magnetic layer is formed on said non-ferromagnetic metal buffer layer. The thickness of the magnetic layer so prepared may be less than 40 ML, close to the limitation of ultrathin. Material for the non-ferromagnetic metal buffer layer is preferably a metal or metal alloy that is immiscible with the magnetic layer when the magnetic layer is formed on the buffer layer. In the embodiments of the present invention, the non-ferromagnetic metal is silver, while material of the magnetic layer is cobalt. This invention also discloses the magnetic structure so prepared.
These and other objectives and advantages of this invention may be clearly understood from the detailed description by referring to the following drawings.